The present invention relates to a pickup device, and more particularly, to a technique for converting the sound of an acoustic musical instrument, such as a piano, into an electrical signal.
There is a pickup device for converting the sound of a piano into an electrical signal. For example, a technique in which the vibration of a string of a piano is detected using a piezoelectric element provided on a bridge has been disclosed in JP-UM-Y-61-034558. In addition, a technique in which a microphone is provided in the vicinity of the soundboard of a piano and the sound emitted from the soundboard is picked up using the microphone has been disclosed in JP-A-7-248760 and JP-A-2007-049578. Furthermore, a technique in which the displacement (twice integration of acceleration) of the soundboard of a piano is detected using a vibration sensor, such as an acceleration sensor mounted on the back surface of the soundboard of the piano, and sound sampling is performed has been disclosed in JP-A-2003-186476.
According to the above-mentioned related-art technique in which the vibration of a string of a piano is detected using a piezoelectric element, only the vibration of the string can be detected and the vibration information of the soundboard is not considered, whereby sound information is insufficient and it is difficult to reproduce the sound of the piano. Besides, the piezoelectric element is required to be mounted on the bridge corresponding to each string, whereby there is a problem that the wiring work and the manufacturing process for the piano become complicated.
According to the above-mentioned related-art technique in which the sound emitted from the soundboard of a piano is picked up using a microphone, part of the sound output from a speaker is fed back to the microphone, whereby there is a fear that howling occurs. In addition, there is a problem of picking up unwanted ambient sound. Furthermore, know-how is required for the setting of the microphone, whereby it is not easy to pick up high quality sound.
According to the above-mentioned related-art technique in which the displacement of the soundboard of a piano is detected using an acceleration sensor, only the displacement in the amplitude direction of the soundboard can be detected. Since the displacement does not directly affect sound pressure (sound pressure is not proportional to the displacement), the obtained sound lacks a sense of reality, and it is difficult to completely reproduce the sound of the piano.